A SINGLE abnormal gene identified by scientists today may be the root cause of birth defects such as spina bifida.

The discovery could lead to new treatments for the devastating disorder, which can result in stillbirth, infant death, or paralysis.

Spina bifida, which affects one in 1,000 pregnancies, belongs to a group of disorders called neural tube defects.

It arises in early pregnancy when the part of the foetus that forms the brain and spinal cord - the neural tube - fails to close properly.

A team of scientists led by Dr Philip Stanier at Imperial College London and Professor Andrew Copp at University College London found the defective "loop-tail" gene in mice which suffer a human-like type of spina bifida.

Prof Copp said, "Our identification of the loop-tail gene is a key finding which will aid in understanding the developmental pathway that regulates neural tube closure. The long term aim of our research is to develop new methods for preventing spina bifida by treating the embryo as it develops during pregnancy."

Previous studies had identified a region of a chromosome where the loop-tail gene was likely to be.

By working out the pattern of DNA components, 12 candidate genes were identified and 11 were shown to be involved in neural tube formation.

Comparing the genetic sequence with that of a "normal" mouse, a mutation in a newly identified gene called Lpp1 was discovered.

Professor Robert Winston, director of research and development at Hammersmith Hospital, said, "We have always suspected that genetic factors may be responsible for these debilitating diseases.

"The discovery that the mutation of a single gene could prevent neural tubes developing normally in the mouse - by stopping the closure of the brain and spinal cord - is important and could offer a potential target for new treatment."